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D6D engine overheating

Lyle niemi

Member
Joined
Sep 25, 2022
Messages
13
Location
Alberta Canada
So I have come to the conclusion my D6D has a cooling problem. It is not a dire cooling problem but it renders the machine unusable for longer periods in summer. The problem is I am pretty sure not in the transmission as it never gets any further then 3/4 of the way through the green, even when the engine reaches the red. The engine will not start running hot until the torque converter gets at least 1/3rd into the green which takes an hour or more. Then if I load the engine up, the temperature it will slowly creep up to the red.

It has done this ever since I bought it a couple of years ago. If I look at the machine I can see the following has been replaced. Transmission water cooler and the transmission radiator cooler, the fan belts are tight and the pulleys are new. The water pump also lacks paint so I suspect it also is new. I pulled the thermostat and checked it and it is fine. The only thing not checked in the engine timing, which I have heard can cause heating issues.

Which leads me to think I know what the problem is. The radiator core which has also recently been replaced. I have flushed it and washed it to no avail, however what I noticed is that the core they used has mighty big gaps between the fins so I looked up the core details which led me to an Australian manufacturer of cores and they list this core as having 6.5 fins per inch, while nearly every other radiator core they make for cat machines lists 9 fins per inch and they list a lot of cores.

So does is sound feasible that they installed a core that the manufacturer puts in the incorrect number of fins for the application, most of the air getting blown through does nothing as it goes no where near the fins.

The core is a 4N6298
I had the same problem with my D6D, never did get it figured out before I sold it .
Someone told me it might be a pre cup issue ??
 

tctractors

Senior Member
Joined
Oct 9, 2007
Messages
2,383
Location
Worc U.K.
A few points to think about, firstly on the Truck water pumps the impeller was often a bit of plastic and would heat up and spin on the pump shaft, the D6D was built with PC and DI engines, water leaks from the Pre Chambers near always are caused by the heat exchanging oil coolers, the transmission also has an air cooler section that comes into play via a temp' regulator, the fan is a blower fan blowing air through the rad', so if you have checked the air filters, the oil coolers? the water pump, the fan, the temp regulator (they do change type) things would point to the radiator or sludge in the cooling system, steam cleaning the rad through with the grill plates and fan guards removed, if it still gets hot its sludge in the water space. tctractors.
 

TBSF

New Member
Joined
Nov 23, 2022
Messages
1
Location
Alberta Canada
I am having similar issues with our D6D. These motors did not have the plastic impellers? I have had the oil cooler temp as high as 230-235 Fahrenheit while the engine coolant temp was 210-215 when measured with a IR heat gun. There is no visible leaks from the water pump or anywhere else in the cooling system. When the machine is not rev’d out the heating problems isn’t as bad but when working under load and rev’d up it heats up.
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,865
Location
WI
When was the last time you looked through the radiator? use a light on the other side, to see how much dirt is plugging it up, not just to see light. Take the temps when the engine is hot like that, 210 or so.
 

oarwhat

Senior Member
Joined
Dec 14, 2009
Messages
824
Location
buffalo,n.y.
I am having similar issues with our D6D. These motors did not have the plastic impellers? I have had the oil cooler temp as high as 230-235 Fahrenheit while the engine coolant temp was 210-215 when measured with a IR heat gun. There is no visible leaks from the water pump or anywhere else in the cooling system. When the machine is not rev’d out the heating problems isn’t as bad but when working under load and rev’d up it heats up.

Check your oil cooler very common problem. It was the OP problem.
 

.RC.

Senior Member
Joined
Nov 27, 2012
Messages
730
Location
Qld, Australia
Well finally got a chance to run the D6D today for a few hours. It was a warm day, the radiator had plenty of water in it, it was reasonably hard work in hills. A couple of hours in the gauge just made it to the red and suddenly spewed a heap of water out the cap. Then proceeded to run as hot as it always did, at the end of the green zone, cooling down when the load went off.
I wonder if I should get rid of that silly transmission radiator cooler that is always semi blocked up and put a full width radiator in it as that is what was fitted to the same series a year or so after mine was built. And pull the precombustion chambers and look at them. I know going by where the glow plugs are located, they were not installed with the correct shims.
 

oarwhat

Senior Member
Joined
Dec 14, 2009
Messages
824
Location
buffalo,n.y.
When we had this problem the oil cooler was really plugged up. Tony (TCtractors) said after cleaning it the radiator often becomes plugged as well. That's exactly what happened to ours. Since our machine was onl used for snowplowing. I did a redneck fix. We cut a hole in the top of the radiator and cleaned out a bunch of junk. Then rodded the tubes with a wire fish. Then taped some holes and made a nice cover. It worked well it started getting warm a year later repeated the process and it never overheated again.
It's better to have it cleaned if you use regularly
 

D6 Merv

Senior Member
Joined
May 10, 2007
Messages
653
Location
Coromandel Peninsula. New Zealand
Occupation
Self employed bulldozing contractor with a D6D D4E
RC, re D6D radiators, later 31X have a much bigger oil to water transmission cooler than the earlier ones oil to water, and then oil to air. Ive got both models and both had overheating problems. Solution was clean trans coolers and new radiators. End of problems. Trans coolers only cause problems if they climb in heat first. And then engine cooling systems can,t handle it. My problems were engine temp climbing first. Had radiators out and dissambled in later one twice before i bit bullet and replaced core with a new one. End of problems. Earlier PC one i didn,t muck around replaced core, and cleaned oil cooler, also end of problems.
 

.RC.

Senior Member
Joined
Nov 27, 2012
Messages
730
Location
Qld, Australia
Sorry for the slow reply. I looked up the parts book and yes it shows a smaller and bigger oil cooler, mine is the smaller as expected.

I have not been using it lately as other stuff has got in the way, but finally got around to putting the rake back on for some new adventures. Blew out the radiator and I was surprised how much came out despite it looking clean. I think at the end of the day the core with the wrong fins per inch is going to be the main cause of the overheating problem. Given it was made by the largest supplier/manufacturer of after market radiators in Australia, beggars belief they got that model wrong. Just has to be my luck.

I will keep using it for the time being and just keep an eye on it.
 

.RC.

Senior Member
Joined
Nov 27, 2012
Messages
730
Location
Qld, Australia
Well it is a year later and this year was one I would rather forget so the dozer did not get driven much and I did nothing about the overheating problems.
As things have improved a bit I am back onto this problem as I have been driving it a bit as weather conditions have improved.

I have started inquiring about a new core. Not cheap it I want to go quality. For locally made brass somewhere around $5000. Steel aftermarket only $2000. The radiator fellow I was talking to did not think 6.5 fins per inch verses 9 fpi would make a massive difference once the 9fpi radiator started to get blocked from debris. He said that was the compromise for increased FPI. Easier to block up from trash, and you also lose air flow because there are more fins to block the air. In saying that the cat specs are 9fpi.

In any case as it is nearly christmas time, a lot of industrial businesses are going to shut end of next week until the 8th January, so I can not do anything there anyway in a hurry.

I have also run it with no radiator guard on. Today I had my temperature gun with me and am getting no more than 5C difference between the top and bottom tank. Hard to get a good measurement, but sometimes it was as low as 3C.

I also found out I am losing a lot of air flow between the gap between the trans oil cooler and the engine cooler, and I need new rubber seals around the fan and there is also some air bypassing around the radiator. In fact I was surprised how low an air flow was going through the radiator compared to blowing through the gaps.

Then there there is also the issue of air exiting the radiator guard, hitting the blade as it is up high dut to the clip on stickrake, the air going down then swirling and getting recycled through the radiator again.

I want to deflect the air upwards as it exits the radiator.
20231216_132220.jpg20231216_132232.jpg
 

OzDozer

Senior Member
Joined
Jan 18, 2007
Messages
2,207
Location
Perth, Western Australia.
Occupation
Semi-Retired ..
RC, I haven't seen any photos of the internals of your cooling system. Does it show clean metal or rusty, scaley, metal?
Scale is a hidden burden in cooling systems, initiated by hard water with minerals in it - even if you're using a good quality coolant. Always use distilled water if you need to add water to cooling systems.

Scale is an excellent insulator and as little as 1/16" (1.6mm) thickness of scale can stop up to 40% of heat transfer.
To get rid of scale, you need to clean out the system with a strong acid or an amine treatment, so that clean metal is again in contact with the coolant.

 

.RC.

Senior Member
Joined
Nov 27, 2012
Messages
730
Location
Qld, Australia
I also found this old post. In 1981, the upper elbow was changed to restrict flow through the radiator to cool the water more, as before it flowed too quickly. Mine is a 77 model.

 

.RC.

Senior Member
Joined
Nov 27, 2012
Messages
730
Location
Qld, Australia
Thanks. Just reading a Cat publication on engine cooling (Know your cooling system SEBD0518-09) and low turbo boost pressure can also cause overheating issues.

Baffles for the radiating cowling I need are 3 of 1P7786 and 1 of 1P7785.

overheating.jpg
 

.RC.

Senior Member
Joined
Nov 27, 2012
Messages
730
Location
Qld, Australia
I priced up the baffles, If I recall correctly Cat wanted over $400 for one and over $150 each for the other 3, not all were in the country anyway.

So I was going to get some rubber belting and cut some out of that, but was not too keen because rubber is pretty soft and has the cotton reinforcement in it. Then I recalled mud flaps are pretty stiff and apparently they are made of urethane plastic.

So off to the truck parts shop today and around $25 for a mudflap, and cut some out of that. To get the right curve for the fan, I drew up a template and 3D printed it. The mudflap was beautiful to cut, much better then rubber sheeting. Upon installation I found I was a bit too generous with by fan dimension and the fan was hitting the rubber. Under a minute later after starting the engine I had it cut to perfection with virtually no gap between the blades and rubber strip. :D :D

I also made up a plug to put in the thermostat to top tank tube. 1.2" diameter as per the specs.

I did give it a run this afternoon and while it seems to be running cooler, I think the main problem is the radiator air hitting the stickrake and blowing back around and getting sucked through the motor.

So I am going to make a wind deflector that will bolt onto the radiator guard. I hope that will be the final piece of the puzzle.

20231218_162200.jpg20231218_140412.jpg20231218_131524.jpg
 

OzDozer

Senior Member
Joined
Jan 18, 2007
Messages
2,207
Location
Perth, Western Australia.
Occupation
Semi-Retired ..
RC, there's a lot of grassy fluff and trash in that core, you need to give it a good squirt with a firefighter hose, with a nozzle on it.
 
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